That is super easy. What you'll be interested in is port (06), that controls what page is swapped in for the $4000-$7FFF range. So values 0 - $7F are flash and $80-$87 are ram.
Here's how you'd do it.
in a, (06)
push af ;make sure to save this for later
ld hl, appName
rst 20h
bcall(_chkFindSym)
jr c, noAppFound ;a = flash page of app
out (06), a
ld hl, $4000
ld de, $9872 ;do whatever with the data
ld bc, $300 ;you can even jump to it and run it
ldir
pop af
out (06), a
And just a few notes: The page you output to port (06) doesn't have to be the app page, you can output whatever you want, but just realize that whatever page you output is what you'll be looking at. And also, you can have the page swapped in for your entire program, Ti OS has no problem with what page is in port (06). Just be sure to put it back when you are done considering that your program returns to somewhere around $6000.